You can manage the mean value of two depreciation methods in a derived depreciation area that links the values of two depreciation areas. In order to do so, you have to identify the derived depreciation area as a mean value area. Instead of the arithmetic mean, you can also link the areas by any mathematical formula you choose.

Linking formula for the mean value:

Depreciation = (depreciation area 1) / 2 + (depreciation area 2) / 2